The invention relates to apparatus for the inregister positioning of a cutting plate on a cutting cylinder, preferably a magnetic cylinder in a rotary printing machine.
More specifically, the apparatus provides exact alignment of the cutting plate, also called a punching plate, on the cylinder.
The mounting of cutting or punching plates on cutting or punching cylinders has been achieved by tensioning means as disclosed, for example, in DE 4,138,278 A1, or by means of bonding as disclosed in DE 2,341,326 C3.
It is also known to use magnetic techniques in a rotary punch construction. In such an instance, the cutting cylinder is designed as a magnetic cylinder which has a multiplicity of powerful magnets (e.g., permanent magnets) distributed over its circumference. A ferromagnetic, formable cutting plate is placed on the magnetic cylinder and is held by magnetic force. The cutting plate has an appropriate cutting edge geometry in order preferably to punch out labels. Magnetic cylinders of this type are disclosed, for example, by the company brochure hpb/10-89/3.d/rt-ra of Kocher & Beck GmbH & Co. Rotationsstanztechnik KG, D-72124 Pliezhausen, Germany.
It is disadvantageous in the latter case that the magnetic cylinders do not permit rapid and exact (and thus in-register) positioning of the cutting plates as a result of the strong magnetic forces of the cylinders. The cutting plate can only be positioned in register with great difficulty since, when the cutting plate is mounted on the magnetic cylinder, the cutting plate is attracted forcefully and in an uncontrollable manner toward the cylinder by the magnetic forces. However, in-register positioning is absolutely essential, for example, when copies have to be perforated, such as in the case of postage stamps.